Spark-plug.



B. SILPA. SPARK PLUG. Arrmouxon nLnn MAY 13, 1911.

1,030,1 35, Patented June 18, 1912.

WITH/E8858 UNITED STATES PATENT OFFICE.

BELISARIO SILF A, OF NEW YORK, N. Y.

SPARK-PLUG.

To all whom it may concern.-

Be it known that I, BELISARIO SILFA, a citizen of the Republic of San Domingo,

Vest. Indies, residing in the city of New' York, borough of Brooklyn, county of Kings, and State of New York, have invented a certain new and useful Spark- Plug, of which the following is a specification.

This invention is a spark plug, the same being more particularly adapted for use in the cylinders of internal combustion engines.

The use of spark plugs'in an engine of the above mentioned type is attended by an accumulation of lubricant, soot or carbon, and other foreign matter, to such an extent as to result in short circuiting the current or to the production of a bridge across the arc gap between the terminals, thus precluding the formation of a spark, interfering with the operation of the engine, and requiring the operator to remove, clean and replace the plug.

The object of this invention is to overcome the'foregoing, and other, objections, and to produce a simple, efiicient, and economical construction wherein the accumulation of foreign matter is minimized so as to obviate the production of a short circuit, one member of the plug being easily removed for cleaning purposes.

A novel feature of the invention resides in the construction of the removable memher, the same comprising a metallic member adapted to form one of the circuit terminals, an insulation of one form or another I substantially enveloping the metallic memher, and a sleeve, composed preferably of lava or porcelain, partially enveloping the insulation, the whole being united into a solid unitary construction, whereby the member is adapted for easy and quick insertion into, or removal from, a bushing, the latter being attached to the engine cylinder by screwing it into the same in any usual or preferred way.

In a practical construction of the remov able member, the insulationconsists of tubes and disks composed of micaslipped upon a metallic rod and positioned in compact order so as to result in, practically, a double insulation, but it is not desired to limit the invention to mica as the insulation, for the reason that porcelain may be used. Mica is the preferred material, for the reason that Specification of Letters Patent. Patented J 1111318, 1912, Application filed Kay 13, 1911.

Serial No. 626,980.

it is more durable andefiicient, porcelain having a tendency to crack and split when heated and exposed to cooling agents suddenly. The durability of the member is increased by the employment of the sleeve, composed preferably of lava, for the reason that the sleeve envelops the insulation for a part of its length, said sleeve being cemented, or otherwise solidly united to the insulation; said sleeve terminating within an end portion of the metallic rod in order to expose the latter.

Another improvement consists in the provision of a recess in the end portion of the bushing, said recess being around the exposed end of the lava sleeve and forming a chamber of such dimensions that any soot, lubricant or other matter will not tend to short circuit the current.

Other features of the invention, and the advantages thereof, will appear from the annexed detailed description taken in connection with the drawings.

In the accompanying drawings I have illustrated different practical embodiments of the invention, butthe constructions shown therein are to be understood as illustrative, only, and not as defining the limits of the lnVQIllZIOIl.

Figure 1 is a sidev elevation of a spark plug embodying this invention. Fig, 2 is an elevation, partly in section, illustrating the means for clamping the removable member in a fixed position within the bushmg. F ig.3is a longitudinal section through the dev ce of Figs. 1 and 2. Fig. at is a longitudinal section through the removable member of the spark plug illustrating another embodiment of the invention.

Referring more particularly to Figs. 1 to 3 of the drawings, 5 designates a bushing, the same being externally threaded for a part of its length, as at 7, whereby said bushing may be screwed into the cylinder of an internal combustion engine for the purpose of fixedly connecting the spark plug to said cylinder. The bushing is provided at one end with an internal or female thread, 25, extending for a part of the length of said bushing, and near its other end said bushing is provided with an internal flange or shoulder, 21, said flange or shoulder being positioned within an open end of the bushing for the purpose of formin a recess or chamber 26, the purpose of which will pres- 1' P P s Said terminal 6 may terial of the bushing, atthe end thereof provided with internal shoulder 21 and recess 26, is a metallic member 6, forming one of the circuit terminals of the spark plug. be composed of any material suitable for the purpose, and it is curved, bowed or deflected for the purpose of bringing its free end into cooperative relation to the other terminal 16 of the spark lug. The removable member of the spark embodies a metallic rod 13, an insulation 27, 9, on said rod, and a sleeve 19 composed .of insulating material and partly incasing the metallic rod 13 and the insulation 9, 21. In .the particular form of the construction shown, the rod 13 is externally threaded for a part of its length toward one end, and at its other end is reduced or provided with a terminal 16, the latter being positioned in cooperative relation to the terminal 6, as clearly shown. At a point-iiitermediate its ends, and preferably toward the end having terminal'16, the rod is provided with a collar or shoulder 17, the latter being fixedly secured to therod in any suitable way, or said collar may be turned on the rod if desired. The members 27 and 9 of theinsulation are composed, preferably, of

'mioa, for the reason that said material is non-combustible and acts efficiently as an electrical insulation. The part 27 of the insulation is in the form of mica tubes which are slipped lengthwise over the rod 13, said tubes being concentric and in compact order. The part 9 of the insulation consists of mica disks placed side by side in close relation to each other, said disks being positioned upo the mica tubes 27.

In .the practical manufacture of the removable member, the mica tubes 27 are slipped upon the rod 13 and upon each other until the tubes abut the collar 17, and thereafter disks- 9, preferably uniform in diameter, are positioned upon the mica tubes so that the disk at one end of the series will abut the collar 17. After assembling the disks, the rod is placed in a lathe and the insulation is turned down so that the disks 9 for a part of the length of the member will be of less diameter than disks 9 .of'another part of the length of the member, the result of the turning operation being to produce va shoulderlg on the insulation, said shoulder being intermediate the two parts which are of diflt'erent'diameters, as shown in Figs. 2 and 3.

The element 19 of the removable member is .a sleeve composed of a hard electrical insulating material, preferably lava, which is turned to the required form and dimensions, although said sleeve may be composed of other insulating material, and it may be molded or otherwise-prepared for use. The sleeve 19 is larger in diameter for a part of in length than another part of the length of said sleeve,'the result being that an internal shoulder 28 and an external shoulder 29 is produced on said sitioned over a partof the metallic rod and the reduced part of the mica insulation so that the internal shoulder 28 of the sleeve will contact with the collar 17, see Fig. 3. A space is left between the chambers of sleeve 19 and the external surfaces of the re-.

duced part of the mica insulation, the collar 17, the part of rod 13 and a part of terminal 16, said spaces being filled with any suitable binding material, such as cement indicated at 28'. The ement operates to unite sleeve .19 solidly to rod 13 and the reduced part of the mica insulation, whereby'the sleeve is sleeve. The sleeve is po-.

attached rigidly to the rod and the insulation so as to constitute a unitary construction. The reduced end portion of sleeve 19 extends beyond the end of the bushing 5 and through recesses or chamber 26. Terminal.-

15 extends a short distance beyond the end .of tube 19, thus exposing the:terminal on the metallic rod in cooperative relation to '90 the terminal 6 in a manner to produce a spark gap across which the current mustump for the purpose of producing the spark required to ignite the charge of combustible vapor within the" engine cylinder.

It should be stated that the mica insulations 9, 27 are clamped rigidly on the. me-- tallic rod between the collar 17 and a washer, 18. A nut 14 is screwed on-the threaded part of rod 13 was to press washer 18 against the mica disks, thereby clamping said mica collar 17 and washer 18. A binding nut 15 is screwed on the threaded end of rod 13, said nut cooperating with nut 14 in clamp;

ing an electrical wire or conductor in me-v tallic contact with the rod 13, thus produc- 1ng a path for the flow ,of current through terminal'16 across the spark gap and into bushing 5, the bushing be terminal 6 and I ing in metallic contact with the cylinder for the purpose of grounding the current, as is usual in the art.

From the foregoing description it is apparent thatthe removable member of the spark plug is adapted to be inserted easily and quickly into the bushing 5. When positioned in the bushing, the removable member is adapted to be retained in a fixed position by clamping said removable member, the clamping operation being efiected by a gland 12 which cooperates with shoulder 10. The bushing 5 is provided intermediate its ends, and adjacent-to the internally threaded part 25 thereof, with an internal shoulder 30, and when removable disks and the mica tubes between.

member is inserted into the bushing, the

with shoulder 10 of the removable member,

whereby the operation of tightening the gland will clamp the shoulder 10 between shoulder 29 of the bushing and the end face of gland 12.

The inner part of sleeve 19 fits snugly within the boreor chamber of the bushing, but to secure a tight joint between the removable member and the bushing at that end, of the plug which is positioned within the engine cylinder, a gasket 20 is slipped upon the reduced part of sleeve 19. This gasket is composed of any non-combustible material, such as asbestos, and

when-the parts are assembled said gasket contacts with the internal shoulder 29 of sleeve 19 and the internal shoulder 21 of the bushing, see Figs. 2 and 3.

From the foregoing description, taken in connection with the drawings, it will be seen that the inner part of rod 13 is insulated from bushing 5 by a triple insulation consisting, first, of mica tubes 27 positioned immediately around the rod 13, mica disks 5 9 externally of the mica tubes, and a lava sleeve 19 positioned around the mica disks, thereby effectually recluding the formation of a short circmt between the metallic rod and the metallic sleeve. The recess or 30 chamber 26 is around that part of the'lava sleeve which projects beyond the bushing, and this recess or chamber provides a space in which lubricant, soot, carbon or any foreign matter may accumulate in such a manner that there is very little, if any, tendency of the formation of a bridge across the spark gap. These two factors contribute very materially to the efliciency of the improved spark' plug. Obviously, gland 12 40 may be unscrewed and the whole removable member may be withdrawn from the bushing, thus exposing all the parts to easy access for the purpose of cleaning them.

The construction shown in Fig. 4: em-

- bodies a porcelain insulating sleeve 31 which may be employed in lieu of mica tubes 27 and mica disks 9. The metallic rod 13 'passes through the porcelain sleeve 31, and this sleeve is providedwith a reduced end portion and with an external collar 10, the latter being the equivalent of the collar 10 of the mica insulation. A lava tube, such as 19, is positioned over the reduced part of tube 31 so as to be united thereto by cement or other suitable medium. The removable member with the tubes 31, 19 and the metallic rod, are adapted to be inserted and retained in position by means similar to those heretofore described. A porcelain so tube, such as 31, istl-iable to crack or split under the action of the heat of an engine, particularly if cold water should drop upon the heated tube, and for this reason it is preferred to employ the mica insulation. 55 Having thus fully described the invention, what I claim as new, and desire to secure by Letters Patent is 1. In a spark plug, a bushing, and a member positioned taerein and removable as a unit therefrom, said member comprising an 7@ electrical conductor, an electrical insulation composed of laminated material and held on said conductor and incasing the latter for a part of its length, an insulating sleeve composed of refractory material and incasing the electrical insulation for a part of its length, said sleeve incasing the electrical conductor for a part of its length and extending beyond the electrical insulation, and cement uniting the conductor and the electrical insulation directly to the insulating sleeve.

2. In a spark plug of the class described, an incased electrical conductor comprising a metallic member provided intermediate its ends with a retaining shoulder, an electrical insulation composed of laminated material and positioned in contact with said shoulder, an insulating sleeve composed of refractory material and incasing the metallic member and the electrical insulation for a part of the length thereof, said sleeve incasing the shoulder and extending forwardly thereof, and cement uniting the incased parts of said insulation and the metallic member directly to said sleeve.

3. In a spark plug, a bushing, an incased conductor positioned within the bushing and removable as a unit therefrom, and means for retaining the incased conductor within the bushing, said incased conductor comprising a central metallic member composed of a single piece and extending continuously through the bushing, an electrical insulation composed of mica and incasing the conductor for a part of its length, and a sleeve composed of refractory material and incasing the metallic member and the electrical insulation for a part of the length thereof, saidsleeve protruding beyond one end of the bushing and said metallic member extending beyond the sleeve; said metallic member, the mica insulation and the refractory sleeve being rigidly secured together.

4. In a spark plug, a bushing provided with an internal shoulder positioned near the inner end thereof, an incased electrical conductor positioned within the bushing and removable as an entity therefrom, and means 1 for clamping said incased electrical conductor within the bushing, said incased electrical conductor comprising a central metallic member, an electrical insulation composed of laminated material and incasing said member for a partof its length, and an insulating sleeve composed of refractory material and united to and incasing the electrical insulation and the metallic member for a part .of the length thereof, said sleeve being provided intermediate its ends with an external shoulder which cooperates with the internal shoulder of the bushing, and said sleeve extending beyond the inner end of said bushing.

5. in a spark plug, a bushing provided with a plurality of internal shoulders, a continuous metallic conductor, an electrical insulation composed of laminated material and inca-sing said metallic conductor, said electrical insulation being provided with an external shoulder which cooperates with one internal shoulder, an insulating sleeve composed of refractory material and incasing the metallic conductor and the electrical insulation for a part of the length thereof.

said sleeve being provided with an external,

shoulder which cooperates with another of the internal shoulders of the bushing, means for clamping the shoulder of the electrical insulation against one shoulder of the bush ing, said sleeve extending beyond the inner end of the bushing, and a packing between the shoulder of the sleeve and one internal shoulder of the bushing.

In testimony whereof I have signed my name of this specification in the presence of two subscribing witnesses.

BELISARIO SILVA.

Witnesses:

M. E. FREEMAN, J. F. MOTHERSHEAD. 

